Automatic choke assembly

ABSTRACT

There is disclosed an automatic choke assembly for use with an internal combustion engine having an intake manifold, an exhaust manifold, an alternator for supplying electrical energy to the engine, at least one carburetor having a conduit therein for supplying air and fuel to the engine, and a valving means for controlling the ratio of the air and fuel. The choke assembly comprises a housing member with a pair of chambers therein, means for supplying heat to a first of said two chambers, a bimetal spring positioned within the first chamber, a heating means thermally connected to the bimetal spring, a terminal contact electrically connected to the engine&#39;&#39;s alternator, and a thermally responsive and electrically conductive member within the second of said two chambers. This assembly provides an interconnection between the heating means and the terminal contact when the temperature about the member exceeds a predetermined level. In doing so, the heating means is energized during engine operation by electrical current supplied from the alternator.

United States Patent [191 Bennett et al.

[451 Aug. 12, 1975 AUTOMATIC CHOKE ASSEMBLY [73] Assignee: GTE SylvaniaIncorporated,

Stamford, Conn.

[22] Filed: June 4, 1973 [21] App]. No.: 366,347

[52] US. Cl 123/119 F; 261/39 R; 261/39 B;

261/39 E [51] Int. Cl. F02d 11/08; F02m l/lO; F02m 23/04 [58] Field ofSearch 123/119 F; 261/39 E, 39 B,

OTHER PUBLICATIONS Ford 1973 Preliminary Car Shop Manual Index Page,pages 24-11-01, 24-11-02, 24-11-03. Printed July, 1972. Ford MarketingCorporation, Dearbom, Mich.

Primary Examiner-Wendell E. Burns Attorney, Agent, or FirmNorman .I.OMalley; Donald R. Castle; Lawrence R. Fraley [5 7 ABSTRACT There isdisclosed an automatic choke assembly for use with an internalcombustion engine having an intake manifold, an exhaust manifold, analternator for supplying electrical energy to the engine, at least onecarburetor having a conduit therein for supplying air and fuel to theengine, and a valving means for controlling the ratio of the air andfuel. The choke assembly comprises a housing member with a pair ofchambers therein, means for supplying heat to a first of said twochambers, a bimetal spring positioned within the first chamber, aheating means thermally connected to the bimetal spring, a terminalcontact electrically connected to the engines alternator, and athermally responsive and electrically conductive member within thesecond of said two chambers. This assembly provides an inter-connectionbetween the heating means and the terminal contact when the temperatureabout the member exceeds a predetermined level. In doing so, the heatingmeans is energized during engine operation by electrical currentsupplied from the alterna- 7 Claims, 4 Drawing Figures AUTOMATIC CHOKEASSEMBLY BACKGROUND OF THE INVENTION The present invention relates tointernal combustion engines and more particularly to automatic chokeassemblies for use with such engines. Automatic choke assemblies asutilized in todays internal combustion engines most usually comprise ahousing member having a bimetallic coil spring therein. This bimetalliccoil spring is heat responsive with the heat being supplied via a ductor similar type heat exchange which derives heat from the exhaustmanifold of the engine. In most prior art automatic choke assemblies ofthe nature described, an inherent problem exists concerning the emissionof waste by-products of the internal combustion engine. This occursprimarily during warm engine operating temperatures when the engine isshut off for a relatively short period of time after which the operatormay soon start the engine again. Upon doing so the above describedbimetallic coil, which has returned substantially to its original unsetcondition, must again be activated. Therefore, when the operator startsthe engine, the choke valving assembly which is directly or indirectlylinked to this coiled spring is usually at the closed position causing arelatively rich mixture of fuel and air to be supplied to the engine. Aquantity of this mixture is thereafter unburned, resulting in thespewing of many undesirable waste by-products from the engine for aperiod of time. This spewing occurs until the previously describedbimetallic spring member again deflects to its fully open positionthereby opening said valving means to provide the proper air to fuelratio for the desired operating conditions of the engine. As can beappreciated, this problem of spewing of excessive hydrocarbons, sulfurdioxide, and other undesirable by-products results in a relatively highrate of pollution of the atmosphere surrounding the operating engine.

It is believed therefore that an automatic choke assembly which wouldprovide a means for heating the bimetallic coiled spring member to afully open position in a relatively short period of time therebyproviding the desired air-fuel ratio in a substantially shorter periodof time than heretofore known would constitute an advancement in theart.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore a primary objectiveof the present invention to provide a new automatic choke assembly foran internal combustion engine.

It is a further object of the present invention to provide an automaticchoke assembly which in turn provides for a more rapid opening of thechoke valve controlling the ratio of air and fuel supplied said engineduring warm engine operating temperatures.

The foregoing objects are achieved in one aspect of the invention by anautomatic choke assembly for an engine having at least one intake andone exhaust manifold, at least one carburetor having a conduit thereinfor supplying air and fuel to the engine, a valving means forcontrolling the ratio of the air and fuel within said conduit, and analternator for supplying electrical energy to the engine. This chokeassembly comprises a housing member having first and second chamberstherein, means for supplying heat to said first chamber, said heatindicative of the temperature of said engine, a bimetallic spring memberpositioned substantially within the first chamber and operativelyconnected to the valving means, a heating means thermally connected tothe bimetallic spring member, a terminal contact member electricallyconnected to said alternator, and a thermally responsive andelectrically conductive member positioned substantially within thesecond chamber. This thermally responsive and electrically conductivemember has at least one arm portion which is thermally and electricallyconnected to the heating means. It also has at least one tongue portionadapted for electrically engaging the terminal contact member when thetemperature surrounding said thermally responsive and electricallyconductive member exceeds a predetermined level. In doing so, theheating means is energized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view insection of the choke assembly of the present invention.

FIG. 2 is an isometric view showing the operation of the bimetalliccoiled spring member of the present invention.

FIG. 3 is an isometric view illustrating the thermally responsiveconductive member of the invention.

FIG. 4 is a partial isometric view showing the relative movement of themember of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding ofthe present invention, together with other and further objects,advantages and capabilities thereof, reference is made to the followingdisclosure and appended claims in connection with the above describeddrawings.

With reference to the drawings, in FIG. 1 there is shown a sideelevational view of one embodiment of the present invention, automaticchoke assembly 10. Assembly 10 is shown to comprise a housing member 11defining a first chamber 13 and a second chamber 15. Positioned withinfirst chamber 13 is the bimetallic spring member 17 which is illustratedas being operatively connected to the choke valving means 19 positionedwithin the conduit 21 of the carburetor assembly 23 which in turn isconnected to an internal combustion engine (not shown), such as is usedin todays automobiles. As is well known in the art, these and similartypes of internal combustion engines comprise at least one intake and atleast one exhaust manifold. Positioned in relationship to the intakemanifold of the engine is at least one carburetor assembly. The functionof this carburetor assembly is to provide the engine with a'mixture ofair and fuel, said air and fuel supplied at a predetermined ratio inorder for the engine to operate'in an efficient manner. An example ofthe previously. described engine arrangement is illustrated in US. Pat.Nos. 3,180,576 and 2,962,014. With particular reference to 3,180,576,the engine is shown to comprise an intake manifold 13, an exhaustmanifold 36, and a carburetor 10 positioned on the intake manifold.Engines of this variety are well known in the art and furtherdescription is not felt necessary.

With particular reference to FIG. 1 which illustrates the presentinvention, the bimetallic spring 17 receives heat from an externalsource. This source, as described in the abovementioned patents, can bethe exhaust manifold of the engine with heat being supplied firstchamber 13 via a means for supplying heat, illustrated as pipe 25. Whenthe engine isinitially started, the bimetallic spring member is in itsunwound position and the valving means 19 is therefore in its normallyalmost closed position as illustrated. In other words, a full choke isnow applied. When the engine is started, air is drawn down throughconduit 21 of carburetor 23 in the direction indicated. This air ismixed with a supplied fuel source (not shown) to provide the desired airto fuel ratio. As can be appreciated, when the valving means is closed,a rich mixture or better defined as a mixture having an excessive amountof fuel therein is derived from the carburetor. Bimetallic coiled springmember 17 is typical of most similar type spring members of chokeassemblies of the prior art and does not provide a means for fullyopening valving means 19 thereby providing the desired air to fuel ratiomixture until the temperature of the engine reaches approximately 120 F.This incurs a time period of approximately 2 minutes in most internalcombustion engines of the automotive and similar fields.

Once the engine has been operated for a period of time and thereafterturned off, bimetallic spring member 17 returns to its normally closedposition. This bimetallic coiled spring will retain the position of thechoke valving means in at least a partially closed position until theengine once again attains the desired operating temperature.Consequently,'upon restarting the engine after a relatively short periodof time, an excessive amount of waste by-products from the engine arespewed into the engines exhaust and thereafter out into the atmospheresurrounding the automobile. To prevent this from occuring, a new andunique assembly is shown in which the bimetallic coiled spring isreturned to a normally open operating position in a relatively shortertime period than previously known automatic choke assemblies. This isaccomplished by providing a thermally responsive and electricallyconductive member 27 within second chamber of housing member 11. Asillustrated in both FIGS. 1 and 3, responsive member 27 comprises atleast one shoulder portion 29 and at least one tongue portion 31. Tongueportion 31 is adapted for engaging a terminal contact member 33 which inturn is electrically connected to I the engines alternator (not shown).When the temper ature about responsive member 27 is at a predeterminedlevel, tongue portion 31 remains engaged with contact 33 therebyproviding an electrical connection between the alternator of the engineand a heating means 35 also positioned'within the second chamber ofhousing 11. Heating means 35 comprises a heater disc member of thermalgenerative material such as barium titanate. Once electrical current issupplied heater member 35, it thereby heats at a relatively high rateand in turn supplies heat to an interconnecting thermal conductivemember 37. As shown in the drawings, the coiled spring member 17 isthermally joined to interconnecting thermal member 37 and is adapted forreceiving heat therefrom. Thus, it can be seen that when responsivemember 27 is in the fully engaged position as indicated in phantom,heating means 35 is actuated thereby providing heat in an indirectmanner to coiled spring 17 during the operation of the internalcombustion engine. This in turn keeps valving means 19 in the fullyopened position. Thus, the desired air to fuel ratio to the internalcombustion engine is'providedina relatively short period of timecompared to the time involved when coiled spring 17 expands solely as aresult of heat from pipe 25. v

With reference to FIGS. 1 and 2, a partial isometric view of coiledbimetallic spring 17 is shown. Coiled spring 17 is positioned withininterconnecting thermal member 37 in the manner indicated. There is alsoillustrated the means by which coiled spring 17 serves to actuatevalving means 19, this achieved by utilizing arm 39 joined to valvingmeans 19 via a rotating shaft 41. As coil spring 17 unwindsin thedirection indicated in FIG. 2 during increases in engine temperature,arm 39 swings choke valving means 19 in the open direction.

Referring particularly to FIG. 1, terminal contact 33 is electricallyconnected to the engines alternator via a connecting plug 43 which isreadily adaptable for engaging a protruding portion of the contact 33.Plug 43 is only representative of several different varieties ofelectrical connection members which are suitable for the presentinvention. A source preferred for supplying heat indicative of theoperating temperature of the engine to first chamber 13 is the enginesexhaust manifold. However, this is not meant to be-restrictive in thatany other type of heating mechanism could successfully be utilizedprovided this mechanism'could directly provide a means for indicatingthe engines operating temperature. As shown in the drawings, heatsupplied from the exhaust manifold to the first chamber 13 is permittedto escape this chamber via a heat removal conduit 45 whichis connectedat its other end to either a lower portion of the carburetor 23 or tothe engines intake manifold. Also shown in FIG. 1 is an optionaladjustment means, illustrated as a screw 46, which can be provided as amethod for adjusting the spacing for the electrical connection betweenContact 33 and responsive member 27. Screw 46 is threaded throughcontact 33 and consequently is electrically connected thereto. Thus, ameans is provided for readily calibrating the engagement cycle betweenthese members according to desired specifications.

A preferred method for providing an electrical ground to the previouslydescribed circuit is to ground thermal conductive member 37; This canbe'achieved by simply affixing an external lead to member 37 which exitsfirst chamber 15 through insulative housing 11. Another relativelysimple grounding means could be achievedrby providing member 37 with aprotruding portion which is adapted for exiting first chamber 13 throughhousing 11. As the above described electrical grounding procedures areeasily understood by those in the art, it is not felt necessary toillustrate them here or to provide further description at this time. Itcan also be readily understood that the described circuit can begrounded at several other locations, for example, members 27 or 35respectively. As stated, however, it is preferred to do so at thermalmember 37.

In FIG. 3 there is shown a more detailed view of thermally' responsiveand electrically conductive member 27. Member 27 is shown to compriseatleast oneshoulder portion 29 and at least one tongue portion 31. In

the preferred embodiment, member 27 comprises a bimetallic member havinga low expansion surface 47 and a high expansion surface 49. Thisbimetallic member is formed preferably from a single or unitary standardsheet of bimetallic material and is available from the w. M. ChaceCompany, Detroit, Mich., sold under thetradename Chace 2400". Chace2400" bimetal has a low expanding side of Invar of 36% nickel with sideof said bimetal is about 10 X 10 per F over a temperature range of fromabout F to about 150 F. Chace 2400 is especially preferred in thepresent invention because bimetallic spring 17 can also be pro.- ducedfrom this material. Terminal member 33 may be of any sound electricalconductive material while it is preferred that the material forinterconnecting thermal conductive member 37 be of a good thermalconductive material such as brass. Housing 11 is preferably of anelectrically insulative material such as the higher heat withstandingplastics, i.e., phenolic.

The preferred embodiment for thermal responsive and electricalconductive member 27 as shown in FIG. 3 comprises two shoulder portions29 and only one tongue portion 31. Shoulder portions 29 are separatedfrom tongue portion 31 by a pair of openings 51. Looking closer attongue portion 31, it can be seen that this portion has the pair ofsubstantially parallel aligned slots 53 formed therein. Slots 53 arelocated longitudinally within tongue portion 31 and define a centralstrip 55 and two exterior lateral strips 57. It is to be understood,however, that slots 53 may be formed in the bimetallic member in anydesired shape and that if desired, may be otherwise fabricated from aplurality of elements. Located on each of exterior lateral strips 57 isan upstanding knee portion 59. As illustrated, central strip 55 is bowedupwardly in comparison to exterior lateral strips 57. Thus, as can beseen in FIG. 4, when the temperature surrounding member 27 attains apredetermined level, central strip 55 will deflect in a downwarddirection in comparison to its previous position. This in turn insures asnap-acting motion by tongue portion 31 to the terminal engagingposition. A preferred temperature range at which the above describedaction takes place is substantially between 80 F and 1 F.

It can therefore be seen that when the engine temperature is within theabove described range of between 80 F and 1 10 F, thermally responsiveand electrically conductive member 27 remains in the engaged positioninterconnecting terminal contact 33 with heating means 35. Thus, if theengine is turned off after operating for a period of time and once againturned on, heating means 35 will be supplied with a flow of electricalcurrent provided the temperature about member 27 is within the preferredrange of from about 80 F to 1 10 F. This supply of current causesheating means 35 to become rapidly heated, thereafter heating bimetalliccoil spring 17 to open choke valving means 19 in a shorter time periodthan herebefore known in the art. When valving means 19 is at an openposition and the engine is at the warmer operating temperature, theproper ratio of air to fuel is attained and fewer waste byproducts areemitted from the exhaust of the engine.

To assure a sound electrical connection between thermally responsive andelectrically conductive member 27 and terminal contact 33, tongueportion 31 has a portion 61 of noble metal affixed thereto. Portion 61,

shownin FlG. 1 as directly engaging a screw 46 and consequently terminalcontact 33 once the described temperatures are attained, is preferablyin the form of a relatively thin sheet of either gold or silver alloyand is'affixed to tongue 31 by any of the several known conventionalmethods of bonding, such as welding.

Thus, there has been described an automatic choke assembly whichprovides for rapid heating of the bimetallic coil element of theassembly to in turn open the choke valving means in the carburetorconduit to thereby assure a more rapid attainment of a proper air tofuel ratio during warmer operating conditions of the internal combustionengine.

While there have been shown and described what are at present consideredto be the preferred embodiments of the invention, it will be obvious tothose skilled in the art that various changes and modifications may bemade therein without departing from the scope of the invention asdefined by the appended claims.

What is claimed is:

1. In an automatic choke assembly for an internal combustion enginehaving intake and exhaust manifolds, at least one carburetor having aconduit therein adapted for supplying air and fuel to said engine, avalving means for controlling the ratio of said air and fuel within saidconduit, and an alternator for supplying electrical energy to saidengine, wherein said choke assembly comprises a housing member definingfirst and second chambers, means for supplying heat indicative of thetemperature of said engine to said first chamber, a bimetallic springmember positioned within said first chamber and operatively connected tosaid valving means, a heating means thermally connected to saidbimetallic spring member, and a terminal contact member electricallyconnected to said alternator, the improvement comprising:

a thermally responsive and electrically conductive member positionedwithin said second chamber, said thermally responsive and electricallyconductive member having at least one arm portion thermally andelectrically connected to said heating means and at least one tongueportion adapted for moving in a snap-action manner to engage saidterminal contact member when the temperature surrounding said thermallyresponsive and electrically conductive member exceeds a predeterminedlevel whereby said heating means is energized during operation of saidengine, said tongue portion comprising a pair of spacedly positionedlateral strip members and a contact strip member positionedsubstantially therebetween, said central strip member separated fromeach of said lateral strip members by a longitudinal slot.

2. The improvement according to claim 1 wherein said thermallyresponsive and electrically conductive member is a bimetal.

3. The improvement according to claim 2 wherein the difference inaverage coefficients of expansion between the high expanding side andthe low expanding side of said bimetal is about 10 X 10 per F over atemperature range of from OF to about 150F.

4. The improvement according to claim 1 wherein said predeterminedtemperature level at which said tongue portion is adapted for engagingsaid terminal contact member is substantially between F and 1 10F.

5. The improvement according to claim 1 wherein each of said lateralstrip members includes at least one upstanding knee portion thereon.

6. The improvement according to claim 1 wherein 7; The improvementaccording to claim 1 wherein said thermally responsive and electricallyconductive member comprises two arm portions thermally and said tongueportion includes a contacting portion of a electrically connected tosaid heating means noble metallic material.

1. In an automatic choke assembly for an internal combustion enginehaving intake and exhaust manifolds, at least one carburetor having aconduit therein adapted for supplying air and fuel to said engine, avalving means for controlling the ratio of said air and fuel within saidconduit, and an alternator for supplying electrical energy to saidengine, wherein said choke assembly comprises a housing member definingfirst and second chambers, means for supplying heat indicative of thetemperature of said engine to said first chamber, a bimetallic springmember positioned within said first chamber and operatively connected tosaid valving means, a heating means thermally connected to saidbimetallic spring member, and a terminal contact member electricallyconnected to said alternator, the improvement comprising: a thermallyresponsive and electrically conductive member positioned within saidsecond chamber, said thermally responsive and electrically conductivemember having at least one arm portion thermally and electricallyconnected to said heating means and at least one tongue portion adaptedfor moving in a snap-action manner to engage said terminal contactmember when the temperature surrounding said thermally responsive andelectrically conductive member exceeds a predetermined level wherebysaid heating means is energized during operation of said engine, saidtongue portion comprising a pair of spacedly positioned lateral stripmembers and a contact strip member positioned substantiallytherebetween, said central strip member separated from each of saidlateral strip members by a longitudinal slot.
 2. The improvementaccording to claim 1 wherein said thermally responsive and electricallyconductive member is a bimetal.
 3. The improvement according to claim 2wherein the difference in average coefficients of expansion between thehigh expanding side and the low expanding side of said bimetal is about10 X 10 6 per *F over a temperature range of from 0*F to about 150*F. 4.The improvement according to claim 1 wherein said predeterminedtemperature level at which said tongue portion is adapted for engagingsaid terminal contact member is substantially between 80*F and 110*F. 5.The improvement according to claim 1 wherein each of said lateral stripmembers includes at least one upstanding knee portion thereon.
 6. Theimprovement according to claim 1 wherein said tongue portion includes acontacting portion of a noble metallic material.
 7. The improvementaccording to claim 1 wherein said thermally responsive and electricallyconductive member comprises two arm portions thermally and electricallyconnected to said heating means.